One factor may be government, vs private parties, control of the companies. For the largest company Equinor, read this quote: The current company was formed by

One factor may be government, vs private parties, control of the companies. For the largest company Equinor, read this quote: The current company was formed by the 2007 merger of Statoil with the oil and gas division of Norsk Hydro. As of 2017, the Government of Norway is the largest shareholder with 67% of the shares, while the rest is public stock. The ownership interest is managed by the Norwegian Ministry of Petroleum and Energy.